Susan has a good idea about taking your pup on very short trips in the car. I would just like to add that make sure all trips aren’t to the shelter/vet. Either drive a few minutes aimlessly or to a fun place like a pet store (maybe during non peak hrs at first since he’s so excitable). Make it positive. Another thing you can do is give him something to do chew while in the car. This will only be for the car. That way it’s “special” and will redirect attention as well as provide an outlet for anxiety.
Some find Rescue Remedy or other calming things like that to be helpful.
I’m glad your dog is doing better. He lucked out and found a great person.
